In wildland fire monitoring, this threshold indicates extreme fire danger. When the relative humidity number falls below the temperature reading, fine fuels on the forest floor dry out rapidly. Fire behavior becomes highly erratic and aggressive, often forcing crews to halt logging operations or shift tactics.
Heard on the job
Humidity is sitting at twenty percent and the temperature just hit twenty-five, so we've a crossover condition and need to shut down the skidder.
Insider tip
Many jurisdictions mandate an immediate shutdown of heavy equipment operations when crossover conditions are met, to prevent sparks from igniting bone-dry slash.